Our main objective is to prepare inhibitors of protein biosynthesis and to study the mechanism of peptide bond formation at the ribosomal level. We have previously completed an extensive study of the ribosome peptidyl transferase center using model substrates and inhibitors of this peptide-forming structure. We plan to extend these studies to find different binding requirements among ribosomes from different sources which will enable us to prepare selective inhibitors of protein synthesis. These agents will have potential as chemotherapeutic agents.